Develop Reference

Variable from javascript function in aspx page accessible in c# code in same javascript function

My code in aspx page is:
<script type="text/javascript">
function MenuItem_Click(itemId) {
<%
MyAspLogger("Clicked on item: {0}", itemId);
%>
}
</script>
I don't know how to access "itemId". I know that from other side - accessing c# variable in aspx code it is possible. But I don't know if is possible access javascript variable in c# code include in same javascript function.
Thank you for your help.

I guess you are tryingto get the clicked menu ids, and then log all clicked menu item?
1- To get the menu id,
Pass the menu object using keyword "this" to the function handling the click (MenuItem_Click).
<a id='menu_1 onclick='return MenuItem_Click(this);'>Click Me!</a>
<script type="text/javascript">
function MenuItem_Click(me) {
alert(me.id); // The Id of menu clicked.
// Do Whatever you want with the id now.
.
.
.
}
</script>
2- Logging clicked menu id
You have 2 options actually ... use a web-service call each time a menu clicked (which I don't recommend)
OR
Use a variable to store the clicked menu ids Or a hidden variable.
<script type="text/javascript">
function MenuItem_Click(me) {
var hdnMenuLog = document.getElementById('hdnMenuLog');
hdnMenuLog.value = hdnMenuLog.value + '|' + me.id;
}
</script>
Hope this helps!

You can not access javascript variable value in server side code until you do postback and send asnc call using ajax. Asp.net generates html and javascript code from server side and sends response to client i.e. browser.
To access javascript variable value after postback you can assign it to some hidden field that is made server accessible and access it on server side code. This is how asp.net maintains ViewState.

I tried
<asp:Label CssClass="helperLabel" runat="server" Visible="False">Test</asp:Label>
<script type="text/javascript">
function MenuItem_Click(item) {
// Setup
$(".helperLabel").html("asdf");
<%
MyAspLogger("Clicked on item");
%>
</script>
in code behind I have
protected void MyAspLogger(string logMessage)
{
MyLogger.Debug(logMessage + "/" + helperLabelId.Text);
}
It's working fine but 2 other issue.
Text is not change on server side but only on client side(saw that after removed Visible attribute from asp control).
And also I found that MyAspLogger method is called on page load not after click event.
What I need is grabb itemId and log that via my Logger method from code behind.
Thank you.

HTML Helper in JavaScript?

In Razor I can do this:
<p #Html.MyCustomDataAttributeFor(person) >#person.Name</p>
To render something like this:
<p data-custom-person-id="1234567890" >Fred</p>
Must I really then do this in (unobtrusive) JavaScript:
$('p[data-custom-person-id="1234567890"]').css('background-color','red');
When I'd prefer to do this:
$('p[#Html.MyCustomDataAttributeFor(person)]').css('background-color','red');
If only I could, otherwise should the data attribute generated by the HTML helper change, my client side code will no longer style the element.

Could you point the script to a .cshtml-file?
<script type="text/javascript" src="/myscript.cshtml"></script>
I think I've done this for both .php and .aspx so I don't see a reason it shouldn't work.
In those cases it makes the server first process the file.
Otherwise you could use a customer HttpHandler that parses whatever text you want server-side before it's sent to the client.
The easiest however, would be to set some Javascript variables from Razor, ie:
<script type="text/javascript">
var customerId = '#Html.MyCustomDataAttributeFor(person)';
</script>
And then write:
$('p[' + customerId + ']').css('background-color','red');

data-custom-person-id="1234567890" is rendered to the browser after server has converted #Html.MyCustomDataAttributeFor(person) to that value. On the client side you will not be receiving these text at all. So, you cannot use those statements for client side styling.

asp.net accessing javascript variables after ajax updatepanel

I'm using AJAX on an ASP.NET web project to update a page. Some of my functions return XML that I want to embed on the page after it reloads. This part works, here's a sample of how it looks at the top of the page:
var productXML = "<?xml version=\"1.0\"?><ArrayOfProduct xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\"><Product><ActualProdID>123</ActualProdID><Name>Test</Name><Description>Test</Description><Edition>Test</Edition><Platform>Test</Platform><Family>Test</Family><Type>Test</Type><DeploymentTypes>Test</DeploymentTypes><BaseActualProdID>Test</BaseActualProdID><Price>0</Price></Product></ArrayOfProduct>";
Later in the page I'm trying to use the XML but it's not working. I tried to do something simple and just throw an alert box in that looks like this:
<script type="text/javascript">
function closeLoading()
{
jQuery('.pleaseWaitPanel').css({ 'display': 'none', 'visibility': 'hidden' });
alert("here");
alert(productXML);
alert("here2");
}
</script>
closeLoading() is called inside:
window.onload = function () { Sys.WebForms.PageRequestManager.getInstance().add_endRequest(closeLoading); };
It loads the jQuery and the first alert "here" works perfect. When I go to alert the productXML, nothing happens. It doesn't throw a JavaScript error, I'm using Firebug. I can confirm the XML is on the page.
Any help on this would be GREATLY appreciated!!

From your code snippets, it looks like your closeLoading function is only being called in your window.onload function. This means that it won't be called after any Ajax request completes as the window won't be reloaded.
I would try moving your call to Sys.WebForms.PageRequestManager.getInstance().add_endRequest(closeLoading) to just before your closing server-side form tag:
<form runat="server">
...
<script>
Sys.WebForms.PageRequestManager.getInstance().add_endRequest(closeLoading);
</script>
</form>
Hope this helps.

var productXML
Is a ServerSide variable, so you don't have access to this in Client script.
If you want to use in a javascript function you can do this :
1) Put the result in a textbox hidden, like
<input type='hidden' value='<%=productXML%>'>
then simply get the value of the textbox.

Calling ASP method inside javascript code

i wonder if there is any way to call an asp method that returns a string or something when you are in <script></script> tags.
Like this (it does not work):
<script language="javascript" type="text/javascript">
function isValid() {
var required = "<%= callAspMethodThatReturnsSomething() %>";
}
</script>
any help with this? thx!

There is no direct way to call c# method like in example above. But you can send $.ajax request to the server, or even send postback using _doPostBack(..,..)

The issue is that you are calling a method on the master page from the content page directly.
You can't do that - you need a reference to the strongly typed master page.
Try this (asp.net 4.0):
<%:((MasterPageClassName)Page.Master).callAspMethodThatReturnsSomething()%>
Or this (pre 4.0):
<%=((MasterPageClassName)Page.Master).callAspMethodThatReturnsSomething()%>

<% callAspMethodThatReturnsSomething() %>
this method in <% %> will work before what you want to do ,it may looks like does not work
yet,you can create a new button on page ,make it unvisible and use it's click event like document.getElementById("<%=button1.ClientID%>").click()

pass a c# variable to javascript function

I'm trying to pass a c# variable as an argument to a java-script function like
<%var count=model.SomeMode.Count();%>
when i pass it to my java script function "checkAll(count)" it does not fire but without the argument its workin fine
CheckAll

Remember the page gets created however you wish. So, you could do something like:
<script type="text/javascript">
var count = <%=model.SomeMode.Count(); %>;
</script>
You could apply the same logic in method calls, so you could do:
CheckAll

Javascript can't see your C# source directly - you need to write it into the Javascript source on the server side:
CheckAll

It should look like this:
<script type="text/javascript">
var count=<%=model.SomeMode.Count()%>;
</script>
Currently you're declaring your variable in C#, not outputting it in the page as a JavaScript one. Instead, you want to declare var count literally in the page and have it set to the output of model.SomeMode.Count().

This might be good for your solution:
<a href="#" onclick='return checkAll(<%=count%);'>CheckAll</a>
But there is an other way of doing this instead of conventional way:
Sharing Variables Between JavaScript and C# by Fredrik Kalseth